A known drive device disclosed in JP2012-172796A (hereinafter referred to as Patent reference 1) includes a motor generator as a drive source, and a one-way clutch, a first gear train, a two-way clutch, and a second gear train as a decelerator.
The drive device disclosed in Patent reference 1 has the motor generator as the drive source, and outputs driving force from the decelerator to drive wheels. The decelerator includes the two-way clutch, the second gear train, the one-way clutch, and the first gear train that are juxtaposed in the aforementioned order on a motor output shaft extending within the decelerator from the motor generator. Alternatively, the decelerator includes the second gear train that contains the two-way clutch and the first gear train that contains the one-way clutch, and the second gear train and the first gear train are juxtaposed in the aforementioned order on the motor output shaft. For example, when the motor generator generates driving force by rotating in a first direction, the driving force rotating the drive wheels in the first direction is outputted by the one-way clutch via the first gear train. When the motor generator generates the driving force by rotating in a second direction that is opposite to the first direction, the driving force rotating the drive wheels in the first direction is outputted by the two-way clutch via the second gear train.
However, according to Patent reference 1, because the decelerator is configured such that the two-way clutch, the second gear train, the one-way clutch, and the first gear train are juxtaposed in the aforementioned order on the motor output shaft extending within the decelerator, or such that the second gear train containing the two-way clutch and the first gear train containing the one-way clutch are juxtaposed in the aforementioned order on the motor output shaft, the axial length of the decelerator in a direction of a rotary axis increases.
A need thus exists for a motor drive device which is not susceptible to the drawback mentioned above.